Taylor Swift put to bed rumours she is romantically involved with her co-star Zac Efron. The Grammy Award-winning singer laughed off the reports as she appeared alongside Efron on the Ellen DeGeneres show, which will air in full today. Swift, 22, and “High School Musical” star Zac, 24, co-star in the animated film “Dr. Seuss’ The Lorax.”

Taylor told Ellen: “We are not a couple. He’s awesome, we are not a couple though. You hear people get together when they’re shooting movies, co-stars. But not like animated co-stars. You know what I’m saying. Oh my god, as we were recording out voiceovers on separate coasts we really connected.”

Zac and Taylor then picked up their guitars and performed a duet as Ellen watched on. They also talked about what they did for Valentine’s Day. Taylor described how she had a ‘pathetic single girls party’ where she ate lots of junk food.

And Zac added: “That’s so different than what single guys do. I went to a screening of a film that I did called ‘Liberal Arts.’ Then cooked some dinner with a friend.”

Rumours began to swirl about the pair after they were spotted sharing a ‘flirty’ meal last month. On January 6, the “New Year’s Eve” star had a ‘flirty dinner with the country superstar’ at an outdoor corner table at LA’s Pace. Us Weekly described how the pair were ‘were deep in conversation and very giggly,’ after arriving together in Efron’s Audi. But the pair have been flirting for a long time. Back in 2009, Efron – single since splitting with Vanessa Hudgens in December 2010 – called Swift a ‘lovely girl, very beautiful.’

In turn, the Grammy-winning singer, dumped by Jake Gyllenhaal in December 2010, gushed that Efron was an ‘all-around amazing guy.’

But an insider in Swift’s camp said: “They were in L.A. doing press stuff together, and after they were done, they decided to grab dinner.”

“They have been friends a long time,” an Efron source says.

Adds another insider. “Taylor thinks Zac’s cute… [but] they are on totally different wavelengths.”

Zac – who recently got his third tattoo etched on his inner arm – has also been linked to Phil Collins’s daughter Lily recently. [Source]